Someone explain group xp vs solo or duo

[Damaja]

I been soloing my new Cleric until today, got 5 for my spells then hit EC for Orc Camp 1. The xp was HORRID in the group and it was a full group, killing 3, or 4 yellow or a couple yellows and a red and only getting 1%. This cant be right, but yea there were some red players in my group but they wernt high enough to keep me from getting no xp so whats going on with the full group xp gain?